Cayetano said the act was "another black eye" for press freedom and further aggravates the country's woeful image as one of the most dangerous places for journalists in the world, next only to strife-torn Iraq.

Expressing concern, she said the incident also "indicates that not even reporters from major media establishments like the Inquirer will be spared by assassins."

"Now the people can't help but be bothered as to who could be next, especially with the national elections drawing near," she added.

The lady senator blamed the government's continuous failure to put an end to the culture of impunity that has allowed the killings of journalists and activists alike to continue.

"The authorities should bring both the triggerman and mastermind to justice, not only in Sonny Mallari's case, but also in the earlier cases of 51 other journalists who just weren't as lucky as him," she said, referring to the running tally by the National Union of Journalists of the Philippines (NUJP) of journalists killed under the watch of the Arroyo administration.

Cayetano said she knew Mallari to be a professional and consummate journalist. "His resourcefulness allows him to cover significant events and breaking news across the region with the aid of modern technology like the mobile phone and e-mail, which he uses to reach out to sources in faraway places."